Of course, most people can learn this. It just takes a decade of continuous study. This is the crux of Flying Lemon's argument: credentials and titles don't mean shit, per se. But they show you have been subjected to a harrowing experience of learning and understanding, and so you have a firm grasp of the topic. If are going to study something deep enough to know it as well as a PhD, then you might as well get one.

Well sorry if I've wasted anyone's time by bringing juvenile ideas into this scholarly setting. Next time I have a half-baked hypothesis, I'll post it in the nether reaches of some science fiction show forum.

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Well, if it helps (probably it doesn't), I don't think anything bad about your post. It's just a harmless, weird idea that popped into someone's mid. Also, it has some similarity with brane cosmology, so it's not completely out of the blue. What I'm arguing against is the position of "it doesn't make sense to me (i.e. I don't understand it), so it must be wrong".

Maths is as "true" as you can get. Literally, you can't make it "truer" than that. But even ignoring that, if you don't speak the language, that would make your opinion about its literature somewhat... limited, don't you think?

But back to the original topic of dark matter, which was created as an ad hoc patch to a cosmology that could not properly account for the structure and movement of galaxies. Dark energy was added after that to balance out problems created by dark matter. Together, these patches make up 95% of the "stuff" in the universe.

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On the other hand, why should the stuff in the universe be intuitive, easy to observe and understand for us? That's just anthropocentrism speaking. Quantum mechanics is definitely counter-intuitive and weird, and yet it's both formally correct and highly predictive. The universe isn't limited by the perspectives of puny brains.

The layman sees one group saying, "The universe is non-intuitive and incomprehensible. You'll just have to trust us." Meanwhile, another group of equally degreed and working researchers says, "It doesn't make sense to us, either. We'd like to suggest an alternative model."

What's weird is that there is nothing special about God, and all the talk against him is some irrational dislike that has no grounds. His existence would be no more weird than the existence of normal people, which are already here. There is no reason for all God to interact through the rest of the forces. And whatever is causing the mass discrepancy is not evenly distributed across space, so it's clearly omnipresent and very powerful, and we call omnipresent/powerful things "god" for some reason. If you like you can believe that God is, say, an invisible particle that doesn't interact through any of the fundamental forces except gravity, go for it, but it is theologically the same thing.

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If that counterargument was conjured by "someone smarter than yourself", then I weep for thee.

It is in that specific sense that cosmology and theology have begun to grow more and more similar: theories are assumed to be correct based less on corroborating data than on a lack of contradictory data.

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I'd love to see the "data" in theology.

Also, given how many confirmed predictions have been carried out based on "dark cosmology", you are talking out of your arse here.

There's plenty of data. It just happens to come from a source that only theologians consider credible.

Also, given how many confirmed predictions have been carried out based on "dark cosmology"...

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Almost without exception, none of those confirmed predictions appear to bear close scrutiny. The observations are invariably tentative and are based on an assumption of the presence of dark matter in the first place, the absence of which would in almost every case suggest a different explanation for the observations.

Actually, I think it's pretty obvious: the predictions related to gravitational attraction and/or the composition and mass distribution of galaxies (or both) is flawed, so those starting assumptions should be corrected first before some unknown and undetectable "other" is inserted into the model.

IOW, scientists shouldn't be looking for exotic "dark matter" particles. They should be looking for other examples of gravitational behavior across galactic distances and/or re-examining the way they calculate the mass of galaxies. The simplest explanation is that they have either under-estimated the mass or under-estimated the effects of gravity at those distances.

Multiple choice: you are given a large wooden box that is labeled "bottled water." You estimate, from the volume of the box, the maximum amount of water the box could contain and therefore work out what its mass should be. Then you try to pick up the box and find out that it's actually 80% heavier than you predicted. How did this happen?
a) You under-estimated the weight of the water
b) You didn't account for the weight of the box itself
c) There's something else in the box in addition to water
d) There is a second invisible box sitting on top of the first box that you cannot see or feel.

Any one of those explanations could fit the facts, but d) is the least plausible by far. They also have different solutions:

a) Check the actual mass/density of water and derive the results yourself
b) Check the mass of the box (or a similar box) without its contents
c) Try to find out for sure what is actually inside the box
d) Devise a series of stupendously convoluted and expensive experiments using setups so sophisticated that the raw data from the results would fill a three-volume encyclopedia.

Again, d) is the least likely to yield meaningful results, especially if you're starting from the basic assumption that there IS an invisible box and that the experiment will eventually bear this out, one way or the other.

IOW, scientists shouldn't be looking for exotic "dark matter" particles. They should be looking for other examples of gravitational behavior across galactic distances and/or re-examining the way they calculate the mass of galaxies.

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We did, and guess what? It was in agreement with a cold dark matter scenario. At the moment of writing this, there is no alternative theory that can adequately explain the behaviour of cosmological structures better than dark matter. And we are talking of a large interval of behaviours, from galaxy rotation curves to gravitational lensing of galaxy clusters. Will a better theory emerge in the future? Obviously, it's possible. Personally, I think that gravity might need some additional work to be completely understood (the above-mentioned brane cosmology is an interesting idea, for example), but as far as I understand it, we won't eschew dark matter in any foreseeable future.

So in the end, I'm sorry, but you have nothing but wishful thinking and anti-establishment rage.

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These comments about physical violence and rage startled me. Has someone here been threatened, maybe been mugged while they were posting to the forum, or perhaps these are reflexive comments—projecting onto others?

Pasty-faced softies however, cloistered away in universities are not much of a challenge; but there are so many of them, like cane toads in the breeding season. And so I now make no bones about how I view blokes who, like K. Thorne and Ned Wright, prance about with long pony tails and matching sandals, or wear earings and otherwise dress and behave like girls (most "male" physicsts nowadays).

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I must ﬁrst apologise, as you for a gentleman I mistook. In all the email you sent me you included rude, arrogant, condescending, stupid, and insulting remarks. You have rightly earnt yourself a bloody nose, and if not for the distance between us I might well have visited you to deliver the causative blow, not because of your incompetent technical argument, but because your behaviour has been that of an arsehole. It seems that you are doomed to live and die a conceited shithead, and, moreover, a conceited shithead who cannot do even elementary geometry.

Your honour, his bloody nose is not a result of rage or violence, there is a much simpler explanation, he underestimated the effects of gravity and his head assumed a trajectory intersecting the doorstep.

These comments about physical violence and rage startled me. Has someone here been threatened, maybe been mugged while they were posting to the forum, or perhaps these are reflexive comments—projecting onto others?

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What, you think I have a low opinion of "independent researchers" just because of their poor math? Hell no.

I get emails from several kinds of people outwith the physics community.

One kind is from people like a pensioner who likes to work through papers as a hobby in his spare time, and he has a few technical questions about how I reached a certain conclusion. He's not a physicist, but he does know his stuff, is curious and I'm happy to answer.

Another is from laymen, members of the public who might have seen something about a paper I've written in New Scientist or Scientific American. Again, happy to oblige as I feel that if physicists are working on research with public funding we should be more than willing to explain what we're doing to them if they ask.

The third category, however, is the "independent researcher", like Crothers etc. A common gambit is that they've solved it all in their heads, and that they want to show me, a professional physicist, so that I can "verify their theory" or basically do their math for them. Usually they have some story about how they've been rejected by others but they know that I'll believe them because I'm different and can see they've got the answer, right?

I now just ignore them because I learned from experience how it will go. A guy emailed me with his weird theory about how humans are here because we are the most effective means of pushing forward entropy, and that I needed to go and verify what he'd done to show he was right.

I engaged with the guy and patiently tried to explain that I didn't think there was much to his idea. I even went and wrote out all the math for him - and got a confrontational reply:

quack said:

"
YOUR A FCUKIN IDIOT. I just called you an idiot because you fully deserved it, moron.

You apparently can't offer anything more than baseless bullshit accusations and lame appeals to authority, instead of addressing the physics. I'VE BEEN LABORING FOR YEARS ON THIS AND YOU HAVE NO FUCKING CLUE.

Your a clown who's let me down just like all the others... I DID NOTHING WRONG. I was just studying gravity and following along with everybody else and then I REALIZED that we NEED to go back to 1917, Einstein but NONE OF YOU WILL LISTEN TO ME.YOU FUCKING CLOWNS are the ones that continually fail to recognize that I have repeatedly given sufficient evidence to warrent that Einstein deserves another little look-see before you can claim a damned thing".

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He was incapable of the work himself, but wanted me to do his calculations for him to reveal the obvious truth that he was right. He was the grand genius, I was to be his Eddington who confirmed his spectacular realization... but because I explained some flaws in his math, I got this aggressive load of bullshit.

Same story with a lot of other theoretical physicists. We swap stories about them. It's not because we're "closed minded", just that many of the "alternative theories" make no sense and are sometimes just plain loopy. I've had emails from delusional "theorists" talking about something called "anti-magnetitism" being suppressed by a conspiracy of Jews and the British Establishment, and mailed manifestos talking about how gravity is really controlled by Atlantis. Of course!

Why are professional scientists often outright dismissive and scornful of "alternative theories"? Quite often because the authors are confrontational fruitloops who are very hard to engage with on any rational level. And at the end of the day, it just isn't worth giving them the time of day.

If I explain why they're wrong to them, I'm either just another Jewish scientist conspiring with Queen Elizabeth II to cover up the wonderful free energy field, or a "willfully ignorant neo-darwinian bully" or some other crap they make up.

There's a reason why many of these guys are out on the fringe: namely that many of them are shrill, ignorant punks who are incapable of showing basic manners, let alone an ability to engage in academic discourse.

And of course, weighting a box of water is exactly the same thing of measuring the gravitational mass of astrophysical objects thousands of light years away from us.

Again, you are seriously underestimating the universe.

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On the contrary, I'm saying that our estimates for the mass of those distant objects is far from certain and difficult to determine for sure, as is the behavior of gravity at galactic/intergalactic distances. Thus the "invisible box" assumption is NOT the one that needs to be investigated and ruled out. To complete the analogy, we're talking about a "box" whose composition and basic properties are not fully understood in the first place, for which existing estimates of its mass and the distribution thereof have a huge degree of error, and for which any solid answer to those questions will be monumentally difficult to obtain in and of themselves. My feeling is that scientists are attacking the more fanciful and exotic theory but never sufficiently ruled out the simpler ones.

We did, and guess what? It was in agreement with a cold dark matter scenario.

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Not exactly. What they found -- in various studies in the early 2000s -- was there was no direct evidence for the alternate explanations, which in a way came down to special pleading for dark matter. Not that I agreed with this particular explanation, but back in 2002 I read a paper in an astronomy journal that sought to debunk the theory that the higher-than-expected angular velocity of distant galaxies could be better explained by a higher-than-predicted population of large brown dwarfs and/or black holes and neutron stars that do not produce strong x-ray signals. The author called that theory "spurious" and concluded -- I kid you not -- that the lack of confirmed brown dwarfs in the Milky Way disproved this theory, and simply ignored the point about black holes/neutron stars.

I remember it now only because it was the first time a scientific journal ever made my jaw drop in disbelief. Mind you, it's not that I actually agree with the theory that brown dwarf populations or non-luminous massive stars by themselves work as an explanation. It's the counter-arguments AGAINST it are and have been deeply fallacious.

At the moment of writing this, there is no alternative theory that can adequately explain the behaviour of cosmological structures better than dark matter...

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Actually there are dozens of theories, many of which are in the process of being tested as we speak. Dark matter isn't the most plausible one, it's merely the most popular.

And we are talking of a large interval of behaviours, from galaxy rotation curves to gravitational lensing of galaxy clusters.

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And little else, it turns out. And even gravitational lensing models are based overwhelmingly on the assumption about the mass distribution of dark matter between galaxies whereas alternate models that assume only slightly different than expected mass distributions still managed to replicate the results.

In such cases, the support for the dark matter hypothesis has been based less on the evidence FOR dark matter than by the reseacher's skepticism for the alternate explanations.

It's also worth pointing out that modified gravity is consistent with virtually ALL of those observations. The only reason scientists question modified gravity is because they're uncomfortable with the idea that general relativity may be at least partially incorrect and/or inapplicable. Relativity itself has become a kind of academic sacred cow that scientists and engineers are reluctant to give the appearance of questioning, even when the theory itself is legitimately inapplicable.

The simplest explanation is that they have either under-estimated the mass or under-estimated the effects of gravity at those distances.

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Since we are fond of educated quotes: "Everything should be made as simple as possible, but not simpler".

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At the risk of inviting a subjective value judgement: when you a discover a contradiction between the model and reality, which solution is simpler?
- Theorizing that reality contains an undetected and fundamentally undetectable factor that is causing the variation
OR
- Theorizing that your model is in some way flawed

"Dark matter" proceeds from the former assumption: the model WOULD work if the universe was heavier, therefore assume the universe is inexplicably heavier and search for the reason why. I'm proposing the alternate hypothesis: the model DOESN'T work and should be replaced with a better one.

Not that I agreed with this particular explanation, but back in 2002 I read a paper in an astronomy journal that sought to debunk the theory that the higher-than-expected angular velocity of distant galaxies could be better explained by a higher-than-predicted population of large brown dwarfs and/or black holes and neutron stars that do not produce strong x-ray signals. The author called that theory "spurious" and concluded -- I kid you not -- that the lack of confirmed brown dwarfs in the Milky Way disproved this theory, and simply ignored the point about black holes/neutron stars.

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Probably because the population of black holes/neutron stars/brown dwarfs needed to explain the behaviour was thousands of time higher the upper end of expected interval determined from stellar evolution.

It's also worth pointing out that modified gravity is consistent with virtually ALL of those observations. The only reason scientists question modified gravity is because they're uncomfortable with the idea that general relativity may be at least partially incorrect and/or inapplicable. Relativity itself has become a kind of academic sacred cow that scientists and engineers are reluctant to give the appearance of questioning, even when the theory itself is legitimately inapplicable.

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That's bunk. Astrophysicists wold be thrilled to find a hole in GR. We are a cutthroat bunch. We crave dismantling other people's theories. That's how we work. Prove good ol' Albert wrong? That would make any scientist cream his pants. The fact that nobody has been able to do that so far is a testament to the robustness of GR.

Yeah, I've never understood this idea that academics are busy hiding things together - I'd (metraphorically) cut the throat of my colleagues as soon as look at then when it comes to research - where's the fun in academia otherwise? You might as well be a teacher.*

* nothing wrong with being a teacher, I was a teacher but I'm an academic we are a different beast.

At the moment of writing this, there is no alternative theory that can adequately explain the behaviour of cosmological structures better than dark matter.

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There is no one dark matter theory.
There are about a dozen dark matter conjectures, each giving dark matter extraordinary and unproven attributes.
And none of these conjectures explain the large scale behavior of galaxies, while being consistent with experimental evidence collected in our neck of the woods (for example, dark matter being completely uniformly spread out, etc).

Dark matter is simply a mathematical placeholder; arguing that we even have a convincing - aka, in accord with all experimental evidence, with properly determined characteristics, etc - conjecture as to what it is says more about the arguer.

Probably because the population of black holes/neutron stars/brown dwarfs needed to explain the behaviour was thousands of time higher the upper end of expected interval determined from stellar evolution.

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Which WOULD have been a valid point to raise and is one of the reasons I don't believe that particular theory either. That's not what worries me.

What worries me is that a surprising number of scientists accept that reasoning as a valid refutation without actually running the numbers to be sure. And the 2002 paper did not even appeal to numbers, but to a variation on the Argument from Incredulity: "If there were a lot of brown dwarfs in the galaxy, why haven't we seen them?"

The reason this worries me is that it demonstrates -- at least among cosmologists -- a willingness to discard possible explanations based less on data and more on preconceptions. When new data is introduced that would otherwise force them to reexamine those preconceptions, the tendency is to try to integrate that new data into the existing model rather than examine the model itself. The result, IMHO, is coming out to be an overly sophisticated model with more exceptions than rules and where the overwhelming majority of actors IN the model have not actually been proven to exist.

Lastly, the VERY worrisome thing about is is that cosmology is inextricably tied up with very expensive and very risk-averse space science projects, telescopes, satellites, laboratories and specialized equipment. With tens of billions of dollars on the line, there's pressure on scientists to achieve useable results, or if they don't, to justify the lack of results, often by calling for even more sophisticated instruments. No scientist -- no matter how honest or professional -- is going to go before the committee that funded a 350 million dollar satellite and tell them "All 50 tests were negative: no sign of dark matter." His career and the careers of his colleagues depends on his ability to spin that as "Our instruments detected [insert technobabble here] which could be consistent with some types of exotic particle processes. It's unclear whether this is suggestive of dark matter or some other process, but with more data the picture might become more clear." I've been in that situation before myself: Your can't say "Fail" so instead you produce a complicated "Did not entirely succeed."

That's bunk. Astrophysicists wold be thrilled to find a hole in GR.

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There ARE several holes in GR. A dizzying number of them, in fact. I'm not speaking hypothetically here, I've been told by astrophysicists specifically that drawing any attention to the problems of General Relativity is an implicitly bad career move in some labs and especially in universities.

There ARE several holes in GR. A dizzying number of them, in fact. I'm not speaking hypothetically here, I've been told by astrophysicists specifically that drawing any attention to the problems of General Relativity is an implicitly bad career move in some labs and especially in universities.

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General Relativity, like Special Relativity, is extremely well-tested and understood. Eddington's experiments, modern GPS satellites... they've all confirmed GR's predictions and we've seen plenty of evidence from astronomical observations too.

Quantum gravity is another matter, where there are plenty of holes and ideas, but cosmological GR is generally pretty much regarded as a success.

There ARE several holes in GR. A dizzying number of them, in fact. I'm not speaking hypothetically here, I've been told by astrophysicists specifically that drawing any attention to the problems of General Relativity is an implicitly bad career move in some labs and especially in universities.

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General Relativity, like Special Relativity, is extremely well-tested and understood. Eddington's experiments, modern GPS satellites...

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Urban legend. GPS satellites don't account for General OR Special Relativity in their calculations -- the degree of error due to time dilation is infinitesimally small and vanishes altogether in the background of larger sources of calculation error. And even if they did, they have to periodically recalibrate their onboard clocks anyway to stay in synch with ground stations.

The basic premise of general relativity -- relativistic gravity -- is verified experimentally. But GR has other problems that are hard to account for.